Digital distributed antenna systems and methods for advanced cellular communication protocols

ABSTRACT

Digital distributed antenna systems and methods for advanced cellular communication protocols are provided. In one embodiment, a digital distributed antenna system comprises: a host unit; a plurality of communication links; a plurality of remote antenna units each coupled to the host unit by one of the plurality of communication links, wherein the communication links transport a downlink digitized RF signal from the host unit to the plurality of remote antenna units, and wherein the remote antenna units are each configured to generate an over-the-air analog RF signal via an antenna from the downlink digitized RF signal; and a localized signal conditioning and control module that extracts from a first digitized RF signal at least one data stream and converts the at least one data stream to baseband data stored in a memory.

BACKGROUND

A typical Digital Distributed Antenna System (DDAS) in the art todayoperate in the downlink direction by providing a point-to-multipointdigital transport for delivering one or more digitized RF signals from acentralized host to a plurality of remotely located antenna units, eachof which broadcast the digitized RF signals as an over-the-air analog RFsignal. Each digitized RF signal carries data samples of a modulatedelectromagnetic radio-frequency waveform. Each of the remote antennaunits in the DDAS receive the same stream of digitized RF signals andeach produces a corresponding analog modulated RF waveform version ofthe digitized RF signals, and broadcast that waveform as an over-the-airRF signal.

A DDAS permits the over-the-air RF signal to cover a much larger andgeographically tailored region because each of the remote antenna units(RAUs) of the DDAS can be specifically located to reach areas whereservice is desired. For example, a one RAU of a DDAS can be placed tocover an outside commons area of a campus while another RAU of the DDAScan be placed within an auditorium on campus because that auditorium'sstructure interferes with reception of signals from the outside.However, with the advent and continued development of Long-TermEvolution (LTE) and other cellular protocols, the modulation of cellularcarrier signals continues to become increasingly complex as compared tolegacy protocols, such as Edge and GSM for example.

For the reasons stated above and for other reasons stated below whichwill become apparent to those skilled in the art upon reading andunderstanding the specification, there is a need in the art for improveddigital distributed antenna systems and methods for advanced cellularcommunication protocols.

SUMMARY

The Embodiments of the present invention provide improved digitaldistributed antenna systems and methods for advanced cellularcommunication protocols and will be understood by reading and studyingthe following specification.

Digital distributed antenna systems and methods for advanced cellularcommunication protocols are provided. In one embodiment, a digitaldistributed antenna system comprises: a host unit; a plurality ofcommunication links; a plurality of remote antenna units each coupled tothe host unit by one of the plurality of communication links, whereinthe communication links transport a downlink digitized RF signal fromthe host unit to the plurality of remote antenna units, and wherein theremote antenna units are each configured to generate an over-the-airanalog RF signal via an antenna from the downlink digitized RF signal;and a localized signal conditioning and control module that extractsfrom a first digitized RF signal at least one data stream and convertsthe at least one data stream to baseband data stored in a memory.

DRAWINGS

Embodiments of the present invention can be more easily understood andfurther advantages and uses thereof more readily apparent, whenconsidered in view of the description of the preferred embodiments andthe following figures in which:

FIG. 1 is a diagram illustrating a digital distributed antenna system ofone embodiment of the present invention;

FIG. 2 is a diagram illustrating a remote antenna unit of digitaldistributed antenna system of one embodiment of the present invention;

FIG. 2A is a diagram illustrating a host unit of digital distributedantenna system of one embodiment of the present invention;

FIG. 3 is a diagram illustrating a digital distributed antenna system ofone embodiment of the present invention; and

FIG. 4 is a flow chart illustrating a method for a digital distributedantenna system of one embodiment of the present invention.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize features relevant to thepresent invention. Reference characters denote like elements throughoutfigures and text.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of specific illustrative embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that logical,mechanical and electrical changes may be made without departing from thescope of the present invention. The following detailed description is,therefore, not to be taken in a limiting sense.

Embodiments of the present disclosure provide digital distributedantenna systems and methods that incorporated localized signalconditioning and control functionality into one or more remote antennalegs comprising a Digital Distributed Antenna System (DDAS). That is,this disclosure proposes that remote antenna units locally process thesignal or incorporate other conditioning and control functionality toimprove the quality of services provided to mobile subscribers. Forexample, in some embodiments, a remote antenna unit would digitallydemodulate a digitized RF signal received from the DDAS host, processthe resulting demodulated signal (either in part or as a whole), andthen digitally re-modulate the signal into a modified digital RF signalthat is provided to radiohead equipment for broadcast. While in basebandform at the RAU, a variety of signal quality enhancements may be appliedto increase the signal to interference ratio for communications beingtransmitted from the RAU to mobile subscriber units. Further, becausethe demodulation, processing, and re-modulation is being performed in adigital domain, particular data streams (for example, specific cellularcommunication channels) can be extracted from the digitized RF signalreceived from the DDAS host for locally specialized processing, whileallowing the balance of other data streams in the digitized RF signal toflow through the RAU without modification.

FIG. 1 is a block diagram illustrating a DDAS 100, of one embodiment ofthe present disclosure. DDAS 100 comprises a host unit 110 coupled to aplurality of remote antenna units (shown at 120-1 to 120-n). The hostunit 110, is coupled to at least one upstream component, such as acellular base station or base transceiver station for example, shown asBS 115. In the downlink direction, DDAS 100 operates as apoint-to-multipoint transport for digitized RF signals. That is,downlink digitized RF signals received by DDAS 100 at host unit 110 froma BS 115 are simultaneously transported to each of the remote antennaunits 120-1 to 120-n. Embodiments described herein may also apply touplink transport of digitized RF signals. As used herein, uplinktransport of digitized RF signals refers to the process of receivingover-the-air RF communication signals from subscriber units at the RAUs120-1 to 120-n of DDAS 100, sampling the analog RF communication signalsto produce uplink digitized RF signals, and summing the uplink digitizedRF signals received from RAUs 120-1 to 120-n at host unit 110 to providea unified stream of digitized RF signals to upstream components, such asBS 115.

In other embodiments, host unit 110 itself may incorporate at least partof the cellular base station functionality of BS 115 integrally with itsfunctions as a DDAS host unit. For example, in other embodiments inoperation, host unit 110 receives from upstream sources such as, but notlimited to analog baseband frequency, analog passband orcarrier-modulated frequency, analog intermediate frequency, or CommonPublic Radio Interface standard (CPRI) signals including digitalbaseband frequency and digital intermediate frequency. It then digitallyup-converts that data into digitized RF signals which are modulated inaccordance with one or more over-the-air cellular modulation protocols.

As shown in FIG. 1, host unit 110 is coupled to RAUs 120-1 to 120-nthrough bi-directional point-to-point communication links 125-1 to125-n. In alternate implementations, communications links 125-1 to 125-nmay be either digital or analog transport links, or combinationsthereof. In the particular embodiment shown in FIG. 1, communicationlinks 125-1 to 125-n are shown as fiber optic links. However, in otherembodiments, other communications means such as but not limited toco-axial cables, CAT-5 cables, or microwave communication links may beutilized in various combinations. As described below, RAUs 120-1 to120-n each include elements for performing various radiohead functionspertinent to generating and transmitting downlink analog modulatedover-the-air RF waveforms and receiving and processing uplink analogmodulated over-the-air RF waveforms.

In the example DDAS 100 shown in FIG. 1, at least one, but notnecessarily all, of RAUs 120-1 to 120-n also utilize localized signalconditioning and control functionality which permits local control andmanipulation of the digital RF signals communicated with host unit 110in order to improve the signal quality of analog RF signals exchangedwith mobile subscriber units 128. For example the RAUs 120-1 and 120-nof DDAS 100 each comprise within the RAU a localized signal conditioningand control module 130. RAUs 120-2, 3 and 4 do not. However, as shown inFIG. 1, in some implementations, one or more of the RAUs may beindirectly coupled to host unit 115, such as shown for RAU 120-3 wherethere is at least one intervening device 111 (which may comprise anintermediate or expansion unit, for example). In one embodiment, thelocalized signal conditioning and control module 130 utilized for RAU120-3 may be implemented in the intervening device 111 rather thanwithin the RAU 120-3. In still other embodiments, the functionalitydescribed for localized signal conditioning and control module 130 maybe implemented for a particular RAU in the host unit 110 as furtherdescribed below. Because each localized signal conditioning and controlmodule 130 for each RAU can be configured to implement differentfunctionalities, a set of local functionalities available to aparticular RAU can be tailored to the needs or conditions relevant tothat particular RAU.

FIG. 2 is a block diagram of an RAU 200 having a localized signalconditioning and control module 205. In at least one embodiment,localized signal conditioning and control module 205 implements themodule 130 described with respect to FIG. 1 above. Any of the options orfunctions attributed to RAU 200 may be attributed to the RAUs 120-1 to120-n described above and vice-versa. RAU 200 comprises components fordownlink digital RF signal processing including localized signalconditioning and control module 205, digital to analog converter (DAC)230, an amplifier 232 and an antenna 234. To support generation of ananalog RF signal for over-the-air broadcast, amplifier 232 includes ahigh power amplifier. The localized signal conditioning and controlmodule 205 comprises a downlink digital demodulator 210, a memory 215, aconditioning and control component 220, and downlink digital modulator225. In one embodiment, digital demodulator 210 and digital modulator225 may be implemented respectively by a digital down-converter (DDC)and a digital up-converter (DUC). In some embodiments, digitaldemodulator 210 may perform digital down conversion if required,followed for example by Air Interface Protocol Decoding/De-Modulationfrom Digitized Baseband RF. In some embodiments, digital modulator 225may perform Air Interface Protocol Encoding/Modulation to DigitizedBaseband RF, followed by digital up conversion to CarrierModulated/Passband RF.

To facilitate upstream transport, RAU 200, further comprises ananalog-to-digital converter (ADC) 240 coupled to antenna 234 viaamplifier 232. ADC 240 produces a string of digital RF signals bysampling an over-the-air uplink analog RF signal received by antenna234. The localized signal conditioning and control module 205 furthercomprises an uplink digital demodulator 255 and an uplink digitalmodulator 260 which are also coupled to memory 215 and controlled byconditioning and control component 220. In one embodiment, digitaldemodulator 255 and digital modulator 260 may be implementedrespectively by a digital down-converter (DDC) and a digitalup-converter (DUC). In some embodiments, the uplink digital demodulator225 will perform digital down conversion from Carrier Modulated orPassband RF to Digitized Baseband RF, followed by decoding/demodulationof the Air Interface Protocol. In some embodiments, uplink digitalmodulator 260 will perform Air Interface Protocol Encoding/Modulation toDigitized Baseband RF, followed by digital up conversion if required.

One or more of the components within RAU 200, including but not limitedto any of demodulators 210 and 225, memory 215, conditioning and controlcomponent 220, or modulators 225 and 260 may be implemented by afield-programmable gate array (FPGA) within RAU 200. In one embodiment,memory 215 stores a data set 216 accessed by conditioning and controlcomponent 220 that defines a set of local signal conditioningfunctionalities available at RAU 200.

In one embodiment in operation, RAU 200, utilizing localized signalconditioning and control module 205, implements a digitized RF signalprocess referred to herein as decode and condition. That is, when RAU200 receives digitized RF signals from host unit 110, module 205demodulates at least part of the digitized RF signal into baseband dataand stores it into memory 215. As the term is used herein, “basebanddata” refers to digital RF samples that have been down-converted and/ordecoded from their as-received modulated state to become Digitized RFsamples representing baseband frequency. A distinction should be notedbetween this Digitized Baseband RF data, and the Digital Baseband datarepresenting the decoded/demodulated Air Interface Protocol. That is,Digitized Baseband RF refers to IQ samples of the Baseband RF signalwhile Digital Baseband refers to decoded/demodulated Air interfaceProtocol (AIP) Layer 1. With respect to the term “Modulation”, it shouldbe appreciated that the term may refer to taking Baseband RF andmodulating it with a carrier. In may also refer to taking an AIP Layer 1signal to Digitized Baseband RF data. Thus two stages of modulationoccur to bring a signal from AIP Layer 2 to a carrier modulated RFsignal: 1) AIP Layer 1 modulation, and 2) baseband to intermediatefrequency or carrier frequency modulation.

As mentioned above, because demodulation is being performed digitally,particular data streams (for example, specific cellular communicationchannels, carriers or sub-carriers) within the received digitized RFsignal can be extracted (for example, decoded at the AIP Layer 2) andstored into memory 215 for subsequent processing, while other datastreams being transported via the digitized RF signal continue to flowthrough RAU 200 RAU unmodified. The extracted stream can also be decodedat AIP Layer 1 in order to process the data and/or obtain a signal tonoise improvement. This could be beneficial due to the forward errorcorrection which may be employed at AIP Layer 1. Extraction/decoding canbe performed on specific sub-carriers in cases where multiple carriershave been combined into a wider slice of RF spectrum, or for specificLTE orthogonal frequencies within the AIP Layer 1.

Once baseband data (either uplink or downlink) has been stored intomemory 215, any number of signal enhancement operations may then beperformed on the stored data by conditioning and control component 220.In one simple embodiment, only AIP Demodulation and AIP Re-Modulationwould be performed in order to reduce system noise. In other embodimentsconditioning and control component 220 can identify that the digitizedRF signal includes a stream of information modulated onto a particularRF channel that, if broadcast as an over-the-air signal, couldexperience local signal quality challenges.

For example, RAU 200 may have a priori knowledge (such as informationstored in a database 217 in memory 215) that indicates a given frequencyis to be avoided (for example, where it is known that a localinterference source is present in the vicinity of RAU 200) because ofpotential degraded transmissions on that RF channel. In that case,conditioning and control component 220 can increase the signal gain ofthe baseband data to increase the signal to interference ratio of there-modulated broadcast of the signal from RAU 200, adjust signal phase,or apply one or more other signal optimizations to overcome theinterference. For example, conditioning and control component 220 canapply a digital pre-distortion based on characteristics known about theinterference (which also may be stored in database 217). That is, whereRAU 200 is aware that the transmitted analog RF signal will encounter acertain distortion due to local environmental conditions, it can apply adigital pre-distortion to the baseband data. Then when the transmittedanalog RF signal encounters the environmental distortion, the sum of theenvironmental distortion with the RAU applied digital pre-distortionwill result in a non-distorted signal being received at the subscriberunit 128. Alternately, conditioning and control component 220 caninstruct digital modulator 225 to avoid the use of that RF channel. Inthat case, digital modulator 225 can up-convert the baseband data ontoanother RF channel, and thus shift the associated stream of informationfrom the poor RF channel. In some embodiments, such as an LTEimplementation, this is coordinated by module 205 with user equipment(UEs) and Evolved Node Bs (eNodeBs) using a control plane. For example,in one embodiment, conditioning and control component 220 will instructdemodulator 210 to extract and down-convert information streams from thedigitized RF signal that are modulated for degraded RF channels, andthen instruct modulator 225 to up-convert the resulting baseband datafor transmission on a better quality RF channel. It should be noted thatwhile this localized signal conditioning is being performed at one RAU(such as RAU 120-1) at a second RAU of DDAS 100, the same informationstream received via the digitized RF signals may simply flow through andbe broadcast without such conditioning, or receive differentconditioning appropriate for the local conditions at the second RAU.

As would be appreciated by one of ordinary skill in the art uponstudying this disclosure, a number of other functions may be applied toinformation streams by conditioning and control component 220. Localizedsignal conditioning performed at a remote antenna unit can overcomeSignal to Interference plus Noise power Ratio (SINR) deteriorations thataffect different areas covered within a DDAS's geographic coverageregion differently, ultimately benefiting data throughput. For example,digital channel condition 220 may perform processing such as, but notlimited to, ciphering (i.e. AIP encoding/decoding) and user-dataconcatenation-segmentation-reassembly, before re-modulating andtransmitting the user data. In one embodiment, conditioning and controlcomponent 220 adds an identification code onto the physical layer thatis different than that of the base station 115 that originated thedownlink digitized RF signal. In one embodiment, the identification codeallows a subscriber unit 128 to differentiate an instance of aninformation stream received from one RAU from another instance of thesame information stream received from another RAU of the same DDAS, oridentify if the information stream being transmitted has been modifiedby the RAU, or has been passed through unmodified from what was receivedat host unit 110.

In other embodiments, conditioning and control component 220 canimplement Layer 2 processing for monitoring/reporting, or even fortransparent RAU based optimization. Such processes would extend beyondjust storing Layer 1 decoded data into memory so it can be read andre-encoded at Layer 1. For example, RAU 200, (via conditioning andcontrol component 220) may transparently implement functions such asmobility control, retransmission control (for example using AutomaticRepeat Request (ARQ)) and user-dataconcatenation-segmentation-reassembly) between the base station 115 andsubscriber units 128. In still further embodiments, physical layercontrol signals which can include a Channel Quality Indicator (CQI), andHybrid ARQ (HARQ) can be extended to an individual RAU, for example sothat the RAU is recognized as a base station from the viewpoint of asubscriber station. In one embodiment, RAU 200 is equipped to providethe same radio protocols as those of an LTE base station, including oneor more of the Packet Data Convergence Protocol (PDCP) for user dataciphering and header compression, Radio Link Control (RLC) protocol forretransmission control by ARQ, concatenation/segmentation/reassembly theService Data Unit (SDU), and in-sequence packet delivery, Medium AccessControl (MAC) protocol for HARQ and user data scheduling and RadioResource Control (RRC) protocol for mobility, quality-of-service (QoS),and security control.

As mentioned above, the functions performed by conditioning and controlcomponent 220 described herein can also be accomplished by locating thelocalized signal conditioning and control module 130 associated with aparticular RAU at the host unit 110 as illustrated in FIG. 2A, oralternatively by performing one or more conditioning and controlcomponent 220 functions at host unit 110 in conjunction with performingone or more conditioning and control component 220 functions at theparticular RAU. Also as mentioned above, one or more conditioning andcontrol component 220 functions may also be performed at localizedsignal conditioning and control module 130 located in an interveningdevice 111 between the host unit 110 and a particular RAU.

FIG. 3 is a block diagram illustrating generally at 300 anotherembodiment of the present disclosure. DDAS 305 comprises a host unit 310and a plurality of RAUs 320. In some embodiments, an RAU 320 may beimplemented using an RAU 120-1 to 120-n or RAU 200 such as describedabove with respect to FIGS. 1, 2 and 2A. In this embodiment, one of theRAUs 320 of DDAS 305 (shown at 326) functions as an over-the-airrepeater unit to transport cellular communications via over-the-airtransmission (indicated by 328) to and/or from a neighboring DDAS orcellular system cell (shown 330).

In one implementation, RAU 326 is configured with and implemented usinga localized signal conditioning and control functionality such as thelocalized signal conditioning and control modules 130 and 205 describedabove. For illustrative purposes, it can be supposed that RAU 326 is belocated at some an extreme distance from host unit 310 such at the edgeof DDAS 305's cell coverage range such that mobile subscribers 128 thatreach this region are supposed to be handed off to another base station.RAU 326 functions as a freestanding repeater module that will store andhold in memory downlink data streams until the subscriber unit issuccessfully handed-off. In one embodiment, downlink information storedat RAU 326 may be forwarded by an over-the-air relay signal 328 from RAU326 to the host unit/base station 345 accepting the subscriber, so thatit may deliver the downlink information to the subscriber unit. Forexample, host unit/base station 345 may be coupled to an RAU 350 thatreceives the over-the-air relay signal 328 from RAU 326 and eithercommunicates it to host unit/base station 345, or directly retransmitsthe downlink information to the subscriber unit itself.

In one embodiment, the set of local functionalities available at any ofthe RAU embodiments described above is static and hard coded into theRAU. In other embodiments, a complete set of local functionalitiesavailable at a particular RAU may be hard coded into the RAU, but theRAU may receive configuration messages from its host unit that can turnparticular functionalizes on or off, or provide other operatingparameters associated with the functionalities. In this way, the set oflocal functionalities can be dynamically tailored at that RAU via thehost unit by the system operator. In still other embodiment, the set oflocal functionalities that are available at an RAU may be modified byrevising sets of implementing code, algorithms and/or parametersexecuted by the RAU, that are received via configuration messages fromthe host unit. In some embodiments, the RAU may provide feedback to thehost unit regarding local operating conditions, from which the host unitmay then decide to revise the set of local functionalities in affect atthat RAU.

Several means are available to implement the various embodimentsdiscussed in this specification. These means include, but are notlimited to programmable hardware including digital computer systems,microprocessors, programmable controllers and field programmable gatearrays. Therefore other embodiments of the present disclosure includeprogram instructions resident on computer readable media which whenimplemented by such programmable hardware, enable them to implement saidembodiment. As used herein, the term “computer readable media” refers totangible memory storage devices having physical forms. Such physicalforms may include any form of computer memory device, such as but notlimited to punch cards, magnetic disk or tape, any optical data storagesystem, flash read only memory (ROM), non-volatile ROM, programmable ROM(PROM), erasable-programmable ROM (E-PROM), random access memory (RAM),or any other form of permanent, semi-permanent, or temporary memorystorage system or device having a physical, tangible form. Programinstructions include, but are not limited to computer-executableinstructions executed by computer system processors and hardwaredescription languages such as Very High Speed Integrated Circuit (VHSIC)Hardware Description Language (VHDL).

FIG. 4 is a flow chart illustrating one method 400 of the presentdisclosure which may also serve as an algorithm for implementing one ormore embodiments such as those describe above. Accordingly, any of theoptions, alternatives or functions attributed to an RAU described abovewith respect to any of FIGS. 1, 2, 2A and 3 may be attributed to the RAUdescribed in this method and vice-versa. The method begins at 410 with adigital distributed antenna system including a host unit, a plurality ofcommunication links and a plurality of remote antenna units each coupledto the host unit by one of the plurality of communication links, whereinthe communication links transports a downlink digitized RF signal fromthe host unit to the plurality of remote antenna units, and wherein theremote antenna units are each configured to generate an over-the-airanalog RF signal via an antenna from the downlink digitized RF signal.The method comprises at 410 receiving a digitized RF signal at alocalized signal conditioning and control module associated with a firstremote antenna unit of the plurality of remote antenna units. Asmentioned above, a localized signal conditioning and control module foran RAU may be located in the RAU, in the host unit, in an interveningdevice between the RAU and the host unit, or a combination thereof. Atthe localized signal conditioning and control module (illustrated at420), the method continues to 422 with extracting from the digitized RFsignal at least one downlink data stream. As mentioned above, extractingmay be performed on specific sub-carriers in cases where multiplecarriers have been combined into a wider slice of RF spectrum, or, forexample, on specific LTE orthogonal frequencies within the AIP Layer 1.

Because extracting/demodulation is being performed digitally, particulardata streams (for example, specific cellular communication channels,carriers or sub-carriers) within the received digitized RF signal can beextracted for subsequent processing, while other data streams beingtransported via the digitized RF signal can flow through the RAUunmodified. The method accordingly proceeds to 424 with down-convertingthe at least one data stream to baseband data (such as digitizedBaseband RF). This step may also comprise AIP Level 1 encoding/decoding.

The method proceeds to 426 with storing the baseband data in a memory.It is expressly noted that once the baseband data has been extracted andstored into memory as described in blocks 422-426, any number of thesignal enhancement operations may then be performed on the stored dataas described in the embodiments described above with respect to FIG.1-3. The method proceeds to 428 with generating an up-converted streamof digital RF data from the baseband data in the memory. This method maybe applied to either uplink or downlink data transport on the DDAS. Inone embodiment where method 400 is being applied to downlink data,method 400 then proceeds with generating at least part of anover-the-air analog RF signal from the up-converted stream of digital RFdata. In one embodiment where method 400 is being applied to uplinkdata, method 400 proceeds with transporting the up-converted stream ofdigital RF data to the host unit where it is combined with uplinkdigital RF signals from the other RAUs into a unified uplink digital RFsignal and communicated to a base station.

The signal enhancements applied by localized signal conditioning andcontrol module to an extracted data stream can include, but are notlimited to signal gain adjustments, signal phase adjustments, shiftsfrom one RF carrier channel to another or fine adjustments to carrierfrequency, and digital pre-distortion. The RAU may also implement withthe base station one or more of mobility control, retransmissioncontrol, user-data concatenation-segmentation-reassembly and/or physicallayer control signals. The Localized signal conditioning and controlmodule can also implement Layer 2 processing for monitoring/reporting,or even for transparent RAU based optimization. Such processes wouldextend beyond just storing Layer 1 decoded data into memory so it can beread and re-encoded at Layer 1. The module may also implement with thebase station one or more of mobility control, retransmission control,user-data concatenation-segmentation-reassembly and/or physical layercontrol signals. For example the localized signal conditioning andcontrol module may transparently implement functions such as mobilitycontrol, retransmission control (for example using Automatic RepeatRequest (ARQ)) and user-data concatenation-segmentation-reassembly)between the base station and subscriber units. In still furtherembodiments, physical layer control signals which can include a ChannelQuality Indicator (CQI), and Hybrid ARQ (HARQ) can be extended to anindividual RAU, for example so that the RAU is recognized as a basestation from the viewpoint of a subscriber station. In one embodiment,the localized signal conditioning and control module is equipped toprovide the same radio protocols as those of an LTE base station,including one or more of the Packet Data Convergence Protocol (PDCP) foruser data ciphering and header compression, Radio Link Control (RLC)protocol for retransmission control by ARQ,concatenation/segmentation/reassembly the Service Data Unit (SDU), andin-sequence packet delivery, Medium Access Control (MAC) protocol forHARQ and user data scheduling and Radio Resource Control (RRC) protocolfor mobility, quality-of-service (QoS), and security control.

Example Embodiments

Example 1 includes a digital distributed antenna system, the systemcomprising: a host unit; a plurality of communication links; a pluralityof remote antenna units each coupled to the host unit by one of theplurality of communication links, wherein the communication linkstransport a downlink digitized RF signal from the host unit to theplurality of remote antenna units, and wherein the remote antenna unitsare each configured to generate an over-the-air analog RF signal via anantenna from the downlink digitized RF signal; and a localized signalconditioning and control module that extracts from a first digitized RFsignal at least one data stream and converts the at least one datastream to baseband data stored in a memory.

Example 2 includes the system of example 1, wherein the first digitizedRF signal is a downlink signal and the over-the-air analog RF signal isgenerated at least in part from the baseband data stored in memory.

Example 3 includes the system of any of examples 1-2, wherein the firstdigitized RF signal is an uplink signal and an uplink digitized RFsignal is generated at least in part from the baseband data stored inmemory.

Example 4 includes the system of any of examples 1-3, wherein thelocalized signal conditioning and control module is implemented in afirst remote antenna unit of the plurality of antenna units.

Example 5 includes the system of any of examples 1-4, wherein thelocalized signal conditioning and control module is implemented in thehost unit.

Example 6 includes the system of any of examples 1-5, wherein thelocalized signal conditioning and control module is implemented in aninterviewing device between a first remote antenna unit and the hostunit.

Example 7 includes the system of any of examples 1-6, wherein basebanddata comprises one or both of Digitized Baseband RF data and DigitalBaseband data.

Example 8 includes the system of any of examples 1-7, the localizedsignal conditioning and control module further comprising: at least onedigital demodulator; a conditioner and control component; the memory;and at least one digital modulator; wherein the digital demodulatorconverts the at least one data stream and stores a result as thebaseband data into the memory.

Example 9 includes the system of examples 8, wherein the digitalmodulator digitally re-modulates the baseband data into a re-modulateddigital RF signal.

Example 10 includes the system of any of examples 8-9, wherein theconditioner and control components applies one or more signaloptimization algorithms to the baseband data.

Example 11 includes the system of any of examples 8-10, wherein theconditioner and control components applies one or more signaloptimization algorithms to the baseband data based on an activated setof functionalities defined in the memory.

Example 12 includes the system of any of examples 8-11, wherein the hostunit is configured to modify the activated set of functionalitiesdefined in the memory.

Example 13 includes the system of any of examples 8-12, wherein thedigital demodulator demodulates the baseband data from a first RFchannel and the digital modulator re-modulates the baseband data onto asecond RF channel.

Example 14 includes the system of any of examples 8-13, wherein theconditioner and control component modifies the baseband data before thedigital modulator re-modulates the baseband data onto a second RFchannel.

Example 15 includes the system of any of examples 1-14, wherein thelocalized signal conditioning and control module applies one or moresignal optimizations to the baseband data.

Example 16 includes the system of any of examples 1-15, wherein the oneor more signal optimizations include at least one of the following:signal gain adjustment; a shift in RF carrier channel; a signal phaseadjustment; and a digital pre-distortion.

Example 17 includes the system of any of examples 1-16, wherein thelocalized signal conditioning and control module is implemented by afield programmable gate array within the at least one remote antennaunit.

Example 18 includes the system of any of examples 1-17, wherein thelocalized signal conditioning and control module implements with thebase station one or more of: mobility control; retransmission control;user-data concatenation-segmentation-reassembly; physical layer controlsignals.

Example 19 includes the system of example 18, wherein the retransmissioncontrol includes implementing Automatic Repeat request (ARQ).

Example 20 includes the system of any of examples 18-19, wherein thephysical layer control signals include one or both of a Channel QualityIndicator (CQI), and Hybrid ARQ (HARQ).

Example 21 includes the system of any of examples 1-20, wherein thelocalized signal conditioning and control module is configured toimplement at least one of: the Packet Data Convergence Protocol (PDCP)for user data ciphering and header compression; Radio Link Control (RLC)protocol for retransmission control by ARQ; in-sequence packet delivery;Medium Access Control (MAC) protocol for HARQ; user data scheduling;Radio Resource Control (RRC) protocol for mobility, QoS, and securitycontrol.

Example 22 includes a method for a digital distributed antenna system,the digital distributed antenna system including a host unit, aplurality of communication links and a plurality of remote antenna unitseach coupled to the host unit by one of the plurality of communicationlinks, wherein the communication links transport a downlink digitized RFsignal from the host unit to the plurality of remote antenna units, andwherein the remote antenna units are each configured to generate anover-the-air analog RF signal via an antenna from the downlink digitizedRF signal, the method comprising: receiving a digitized RF signal at alocalized signal conditioning and control module associated with a firstremote antenna unit of the plurality of remote antenna units; with thelocalized signal conditioning and control module: extracting from thedigitized RF signal at least one data stream; down-converting the atleast one data stream to baseband data; storing the baseband data in amemory; and generating an up-converted stream of digital RF data fromthe baseband data in the memory.

Example 23 includes the method of example 22, wherein, the methodfurther comprises: generating at least part of the over-the-air analogRF signal by up-converting the baseband data in the memory.

Example 24 includes the method of any of examples 22-23, wherein, themethod further comprising: transporting the up-converted stream ofdigital RF data to the host unit where it is combined with uplinkdigital RF signals from at least one other remote antenna unit into aunified uplink digital RF signal.

Example 25 includes the method of any of examples 22-24, wherein thefirst remote unit comprises a conditioner and control component, themethod further comprising: with the conditioner and control component,applying one or more signal optimizations to the baseband data.

Example 26 includes the method of example 25, wherein the one or moresignal optimizations include at least one of the following: a signalgain adjustment; a shift in RF carrier channel; a signal phaseadjustment; and a digital pre-distortion.

Example 27 includes the method of any of examples 25-26, wherein theconditioner and control components applies one or more signaloptimizations to the baseband data based on an activated set offunctionalities defined in a memory.

Example 28 includes the method of any of examples 25-27, wherein thehost unit is configured to modify the activated set of functionalitiesdefined in the memory.

Example 29 includes the method of any of examples 25-28, wherein withthe conditioner and control component, the method further comprisesimplementing on or more of: mobility control; retransmission control;user-data concatenation-segmentation-reassembly; physical layer controlsignals.

Example 30 includes the method of example 29, wherein the retransmissioncontrol includes implementing Automatic Repeat request (ARQ).

Example 31 includes the method of any of examples 29-30, wherein thephysical layer control signals include one or both of a Channel QualityIndicator (CQI), and Hybrid ARQ (HARQ).

Example 32 includes the method of any of examples 22-31, wherein thelocalized signal conditioning and control module modulates the basebanddata onto a different RF channel than an RF channel from which it wasdown-converted from.

Example 33 includes the method of any of examples 22-32, wherein withthe localized signal conditioning and control module, the method furthercomprises implementing on or more of: the Packet Data ConvergenceProtocol (PDCP) for user data ciphering and header compression; RadioLink Control (RLX) protocol for retransmission control by ARQ;in-sequence packet delivery; Medium Access Control (MAC) protocol forHARQ; user data scheduling; Radio Resource Control (RRC) protocol formobility, QoS, and security control.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiment shown. This applicationis intended to cover any adaptations or variations of the presentinvention. Therefore, it is manifestly intended that this invention belimited only by the claims and the equivalents thereof.

What is claimed is:
 1. A digital distributed antenna system, the systemcomprising: a host unit; a plurality of communication links; a pluralityof remote antenna units each coupled to the host unit by one of theplurality of communication links, wherein the communication linkstransport a downlink digitized RF signal from the host unit to theplurality of remote antenna units, and wherein the remote antenna unitsare each configured to generate an over-the-air analog RF signal via anantenna from the downlink digitized RF signal; and a localized signalconditioning and control module that extracts from a first digitized RFsignal at least one data stream and converts the at least one datastream to baseband data stored in a memory.
 2. The system of claim 1,wherein the first digitized RF signal is a downlink signal and theover-the-air analog RF signal is generated at least in part from thebaseband data stored in memory.
 3. The system of claim 1, wherein thefirst digitized RF signal is an uplink signal and an uplink digitized RFsignal is generated at least in part from the baseband data stored inmemory.
 4. The system of claim 1, wherein the localized signalconditioning and control module is implemented within at least one of: afirst remote antenna unit of the plurality of antenna units; the hostunit; or an interviewing device between a first remote antenna unit andthe host unit.
 5. The system of claim 1, wherein baseband data comprisesone or both of Digitized Baseband RF data and Digital Baseband data. 6.The system of claim 1, the localized signal conditioning and controlmodule further comprising: at least one digital demodulator; aconditioner and control component; the memory; and at least one digitalmodulator; wherein the digital demodulator converts the at least onedata stream and stores a result as the baseband data into the memory. 7.The system of claim 6, wherein the digital modulator digitallyre-modulates the baseband data into a re-modulated digital RF signal. 8.The system of claim 6, wherein the conditioner and control componentsapplies one or more signal optimization algorithms to the baseband data.9. The system of claim 6, wherein the digital demodulator demodulatesthe baseband data from a first RF channel and the digital modulatorre-modulates the baseband data onto a second RF channel.
 10. The systemof claim 6, wherein the conditioner and control component modifies thebaseband data before the digital modulator re-modulates the basebanddata onto a second RF channel.
 11. The system of claim 1, wherein thelocalized signal conditioning and control module applies one or moresignal optimizations to the baseband data.
 12. The system of claim 11,wherein the one or more signal optimizations include at least one of thefollowing: a signal gain adjustment; a shift in RF carrier channel; asignal phase adjustment; and a digital pre-distortion.
 13. The system ofclaim 1, wherein the localized signal conditioning and control moduleimplements with the base station one or more of: mobility control;retransmission control; user-data concatenation-segmentation-reassembly;physical layer control signals.
 14. The system of claim 1, wherein thelocalized signal conditioning and control module is configured toimplement at least one of: Packet Data Convergence Protocol (PDCP) foruser data ciphering and header compression; Radio Link Control (RLC)protocol for retransmission control by ARQ; in-sequence packet delivery;Medium Access Control (MAC) protocol for HARQ; user data scheduling;Radio Resource Control (RRC) protocol for mobility, Quality of Service(QoS), and security control.
 15. A method for a digital distributedantenna system, the digital distributed antenna system including a hostunit, a plurality of communication links and a plurality of remoteantenna units each coupled to the host unit by one of the plurality ofcommunication links, wherein the communication links transport adownlink digitized RF signal from the host unit to the plurality ofremote antenna units, and wherein the remote antenna units are eachconfigured to generate an over-the-air analog RF signal via an antennafrom the downlink digitized RF signal, the method comprising: receivinga digitized RF signal at a localized signal conditioning and controlmodule associated with a first remote antenna unit of the plurality ofremote antenna units; with the localized signal conditioning and controlmodule: extracting from the digitized RF signal at least one datastream; down-converting the at least one data stream to baseband data;storing the baseband data in a memory; and generating an up-convertedstream of digital RF data from the baseband data in the memory.
 16. Themethod of claim 15, wherein, the method further comprising: generatingat least part of the over-the-air analog RF signal by up-converting thebaseband data in the memory.
 17. The method of claim 15, wherein, themethod further comprising: transporting the up-converted stream ofdigital RF data to the host unit where it is combined with uplinkdigital RF signals from at least one other remote antenna unit into aunified uplink digital RF signal.
 18. The method of claim 15, whereinthe first remote unit comprises a conditioner and control component, themethod further comprising: with the conditioner and control component,applying one or more signal optimizations to the baseband data.
 19. Themethod of claim 18, wherein the one or more signal optimizations includeat least one of the following: a signal gain adjustment; a shift in RFcarrier channel; a signal phase adjustment; and a digitalpre-distortion.
 20. The method of claim 18, wherein with the conditionerand control component, the method further comprises implementing on ormore of: mobility control; retransmission control; user-dataconcatenation-segmentation-reassembly; physical layer control signals.21. The method of claim 15, wherein the localized signal conditioningand control module modulates the baseband data onto a different RFchannel than an RF channel from which it was down-converted from. 22.The method of claim 15, wherein with the localized signal conditioningand control module, the method further comprises implementing on or moreof: the Packet Data Convergence Protocol (PDCP) for user data cipheringand header compression; Radio Link Control (RLC) protocol forretransmission control ARQ; in-sequence packet delivery; Medium AccessControl (MAC) protocol for HARQ; user data scheduling; Radio ResourceControl (RRC) protocol for mobility, Quality of Service (QoS), andsecurity control.